1. Field of the Invention
The present invention relates to a process for producing a liquid ejection head.
2. Description of the Related Art
A recording apparatus (liquid ejection apparatus) using an ink jet system has a configuration for performing recording by ejecting an ink (recording liquid) droplet from an ejection orifice of a nozzle of a recording head and causing the ink droplet to adhere to a recording medium.
A configuration of the liquid ejection head of this type is described below. The liquid ejection head includes a silicon substrate in which electric wiring, ejection energy generating elements for generating energy for ejecting ink, and the like are provided on a surface thereof. On the silicon substrate, multiple nozzles are provided. Each of the nozzles includes a bubble generating chamber for generating a bubble using the ejection energy generating element, a minute ejection orifice for ejecting ink droplets, a flow path for supplying ink, and the like. Further, the silicon substrate has an ink supply port provided therein for supplying ink from the outside so as to pass through a front surface and a rear surface of the silicon substrate. As for the ink supply port, there are known a configuration in which ink is directly supplied from a common liquid chamber to the nozzles, and a configuration in which ink is supplied from the common liquid chamber to the nozzles via independent supply ports.
In the liquid ejection head having the configuration described above, ink supplied from the rear surface side of the silicon substrate is supplied through the ink supply port to the respective nozzles, and is filled in the bubble generating chamber. The ink filled in the bubble generating chamber is ejected in a direction substantially orthogonal to the silicon substrate due to a bubble generated through film boiling by the ejection energy generating element. In this manner, ink droplets are ejected from the ejection orifice.
In Japanese Patent Application Laid-Open No. 2010-131954, on a substrate, a positive photosensitive resin is formed to be used as a pattern corresponding to a shape of a liquid flow path. When the positive photosensitive resin is exposed to light, an exposure apparatus for exposing the entire substrate to light at one time at a magnification of 1 to 1 is used because of a required exposure amount. The exposure apparatus performs exposure at one time, and hence the accuracy of alignment between the substrate and a mask may be insufficient. In particular, as the substrate is upsized, the alignment accuracy may vary within the same substrate or depending on the substrate due to warpage of the substrate or the like. In Japanese Patent Application Laid-Open No. 2010-131954, as a countermeasure for such a problem, a mask layer capable of reducing transmission of light having a photosensitive wavelength is provided on a part of a photosensitive resin layer corresponding to the liquid flow path, and the photosensitive resin layer is exposed to light at one time with use of the mask layer as a mask, to thereby form a desired flow path mold in the photosensitive resin layer. The mask layer can be patterned with high positional accuracy with use of the most widely-used i-line (365 nm) stepper having high alignment accuracy. Along therewith, the positional accuracy of patterning in the photosensitive resin is also improved. After that, a layer that becomes a nozzle member is provided so as to cover the liquid flow path pattern, and then ejection orifices are formed in parts of the layer. Then, the flow path pattern is removed. Thus, the liquid ejection head is produced.